Best in HW2: Voridus.
His kit synergizes really well with the mini-steal chopper jpb rush, which shuts down unsc really hard. vs other Banished he can just spam grunts and farm combat spoils in order to out eco them. Not just that, but having to panic buy minis hurts your eco a lot early on, so Vori almost always has an edge.
Best in HW1: Anders.
She's easily the most versatile leader due to her unique unit and ability. Cryo lets you canny glitch and cryo-jack, while gremlins give you the upper hand in tank v tank engagements. You can also stun-jack with them. It's impossible to keep her on one base as Covies, as every time you go on offense there will be a counter push. She can get Gauss, Wingmen, and reserves very cheap and quickly as well, which is a death sentence for Covie most of the time.